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From the perspective of both fundamental and applied science, it is extremely advisable to develop a facile and feasible strategy for fabricating gels with defined structures. Herein, the authors report the rapid synthesis of patterned gels by conducting frontal polymerization (FP) at millimeter‐scale (2 mm), where a series of microchannels, including linear‐, parallel‐, divergent‐, snakelike‐, circular‐ and concentric circular channels, were used. They have investigated the effect of various factors (monomer mass ratio, channel size, initiator concentration, and solvent content) on FP at millimeter‐scale, along with the propagating rule of the front during FP in these microchannels. In addition, we developed a new microfluidic‐assisted FP (MFP) strategy by combining the FP and microfluidic technique. Interestingly, the MFP can realize the production of hollow‐structured gel in a rapid and continuous fashion, which have never been reported. Our work not only offers an effective pathway towards patterned gels by the microchannel‐conformal FP, but also gives new insight into the continuous production of hollow‐structured materials. Such a method will be beneficial for fabricating vessel and scaffold materials in a flexible, easy‐to‐perform, time and energy saving way. [ABSTRACT FROM AUTHOR]

The ability to fabricate high-quality colloidal photonic crystal (CPC) films in large areas is critical in many applications, ranging from flexible displays, security devices to optical enhancement. Herein, a large-scaled CPC film with crack-free structure and uniform optical performance is prepared via a hydrogen-bond-assisted method. The crack-free CPC film is ascribed to the intermolecular hydrogen bonds between carboxyl (COOH) moieties of poly(styrene-methyl methacrylate acrylic acid) microspheres and isocyanate (NCO) moieties of polyurethane. Furthermore, the as-prepared CPC film is applied as a Bragg reflection mirror for fluorescence enhancement. It is demonstrated that a fourfold enhancement of fluorescence signal is achieved when the stopband of CPCs overlaps with the emission wavelength of quantum dots. This simple method of preparing large-area and crack-free CPC film is promising for developing efficient optical devices. [ABSTRACT FROM AUTHOR]

We report a simple and effective route to easily prepare multi-emission carbon dots (CDs) and CdTe/carbon highly fluorescent assemblies by employing general and low-cost ubiquitous herbages as carbon source. Four kinds of herbages including radix pseudostellariae, ganoderma, liquorice, and angelica were pyrolyzed to straightly generate narrow-size distributed bare CDs. The as-prepared bare CDs have excellent solubility in various organic solvents without further treatment and exhibit bright photoluminescence with the quantum yields up to 28 %. After further treatment with nitric acid and amine-terminated compound 4,7,10-trioxa-1,13-tridecanediamine, the passivated CDs can be combined together with traditional CdTe QDs to form new ensembles for evoking their collective properties. The resulted CD solutions were proven that can be employed as fluorescent inks for patterning which may useful in anti-counterfeit and optoelectronic devices. [ABSTRACT FROM AUTHOR]

ABSTRACT We report the facile synthesis of poly(VI- co-MAA) superabsorbent polyampholytic hydrogels (VI = N-vinylimidazole, MAA = methacrylic acid) via plasma-ignited frontal polymerization (PIFP). On igniting the top surface of the reactants with air plasma, frontal polymerization occurred and poly(VI- co-MAA) hydrogels were obtained within minutes. The preparation parameters were investigated, along with swelling capacity, morphology, and chemical structures of poly(VI- co-MAA) hydrogels. Interestingly, the hydrogels are superabsorbent in water and show ampholytic characteristic toward pH. Moreover, the hydrogels are able to capture cationic dyes through electrostatic interaction, offering the potential for further development as dye adsorbents for water purification. In addition, nanocomposite hydrogels were obtained by embedding quantum dots (carbon dots or CdS nanocrystals) into the polymer matrix, which endows the nanocomposite hydrogels with favorable fluorescence and potential applications in bioimaging and biosensing. The results indicate that FP can be applied as an alternative means for facile synthesis of multifunctional hydrogels with additional efficiency and energy-saving. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 912-920 [ABSTRACT FROM AUTHOR]

We report herein the synthesis of carbogenic dots (CDs) by a one-step pyrolysis from N-acetylcysteine. The as-prepared CDs show excellent dispersibility with particle sizes in the range of 3-5 nm. Under stimulation with blue light, the CDs emit broad yellow fluorescence, which is still rarely reported by now. The optical properties were throughly investigated, and we found the CDs exhibit stable fluorescence, high quantum yield, and pH dependence. Moreover, an economical approach for constructing white light-emitting diodes (LEDs) was developed by combining the yellow-emitting CDs with blue GaN-based LED chips. The white LEDs exhibit warm white light with the color coordinates of (0.34, 0.35), very close to the coordinates of balanced white-light emission (0.33, 0.33). These results suggest that the CDs can be a promising candidate as yellow-emitting phosphor for white LEDs. [ABSTRACT FROM AUTHOR]

Methods for the synthesis of chiral carbon dots (CDs) possessing bright long-wavelength emission are highly desirable. Here, we develop red-emissive chiral CDs from hydrothermal treatment of L-/D-lysine and o -phenylenediamine (OPD). Pure chiral CDs are obtained by filtration and dialysis. Ultraviolet-visible (UV–vis) absorption spectra, photoluminescence (PL) spectra, PL quantum yield (QY), and PL decay of the chiral CDs are thoroughly studied. The chiral CDs exhibit bright red fluorescence with PL QY in the range of 26.6%–42.2% in different solvents. Transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, and X-ray photoelectron spectroscopy (XPS) indicate that the chiral CDs have a mean particle size of 2.7 nm, and consist of graphite-like carbons and abundant functional groups at their surfaces. Circular dichroism spectroscopy shows new Cotton bands at about 300 and 610 nm for chiral CDs differed from those of L-/D-lysine, revealing the generation of optical chirality for CDs. Then transparent optical resins made of CDs/epoxy resin composites are prepared, possessing red fluorescence and circular dichroism, broadening potential applications of solid materials with chiroptical properties. Finally, we discuss the possible origins of chirality and fluorescence of the CDs. The exploitation of highly red-emissive chiral CDs may promote the development and application of chiral CDs. [Display omitted] • L-/ d -lysine reacts with o -phenylenediamine to yield chiral carbon dots (CDs). • Structural, optical and chiroptical characterizations of chiral CDs are presented. • Chiral CDs show red fluorescence with quantum yield up to 42.2%. • Circular dichroism spectroscopy reveals the generation of optical chirality for CDs. • Optical resins with red fluorescence and circular dichroism are prepared. [ABSTRACT FROM AUTHOR]

[Display omitted] • Microfluidic chip is created for rapid and continuous synthesis of carbon dots (CDs). • CDs have high quantum yield of 71% and excellent optical stability. • CDs/polymer nanofibers are continuously produced via electro-microfluidic spinning. • Nanocomposite fibers have uniform fluorescence and enhanced mechanical properties. Carbon dots (CDs) have shown great promise in various fields owing to their fascinating properties. However, most of high-performance CDs are usually synthesized upon intermittent operations, which are difficult to produce continuously in batch. In this regard, we develop a robust aluminum-based microfluidic chip reaction platform with imbibition-injection cycle feeding and ease of scale-up production, allowing the rapid and continuous synthesis of highly fluorescent CDs. The as-prepared CDs possess excellent optical properties, including high photoluminescence (PL) quantum yield (QY) of 71%, narrow full width at half maximum (FWHM) of 65 nm by optimizing the parameters of reaction. Combined with electro-microfluidic spinning, the continuous production of fluorescent enriched CDs/polymer nanofibers could further be realized. CDs/thermoplastic polyurethane (TPU) and CDs/polyamide 6,6 (PA66) nanofibers are prepared to exhibit enhanced mechanical properties with tensile strength 2.9 and 4.1 times higher than those of the pure polymer matrix, respectively. This work contributes a new kind of microfluidic chip for nanomaterial synthesis, and paves a way toward rapid and continuous preparation of high-performance CDs and CDs/polymers nanofiber films by microfluidic techniques. [ABSTRACT FROM AUTHOR]

Surface-passivatedphotoluminescent carbon dots (CDs) were preparedvia a facile one-step pyrolysis of poly(acrylic acid) (PAA) in thepresence of glycerol. In the formation process of CDs, glycerol notonly acts as solvent, but also promotes the carbonization of PAA (carbonsource) and passivates the surface of CDs. The as-prepared CDs canemit bright-white fluorescence under ultraviolet (UV) illumination.The structure and optical properties of the CDs were thoroughly investigated.The CDs show excellent solubility in water and high photoluminescencestability in UV-radiation, salty, oxidic, or reductive environments,suggesting their great promise as white-light-emitting materials.For their practical applications, a white light-emitting diode (LED)with CDs as white-light converters was demonstrated. Moreover, a backlightwith use of CDs as coatings was successfully constructed for the firsttime. This research would offer a promising new way to obtain whitefluorescent CDs and suggests their strong potential for solid-statelighting systems. [ABSTRACT FROM AUTHOR]

Bottom-up methods allowing the preparation of carbon dots (CDs) with favorable attributes are highly desirable. Herein, we report the mild bottom-up synthesis of CDs towards temperature sensing. Five kinds of CDs with blue or green fluorescence were synthesized in water or tetrahydrofuran (THF) under moderate conditions (normal pressure, 50~95 °C), with use of carbonyl compounds as carbon sources, such as acetylacetone (AA), cyclohexanone (CH), 2-hydroxy-2-methylpropiophenone (HM), glutaric dialdehyde (GD), and salicylaldehyde (SA). Typically, with use of acetylacetone (AA) as carbon sources, CDs were synthesized at 95 °C in water in the presence of zinc chloride and 1, 2-dichloroethane. The synthesis, characterizations, and optical properties of AA-derived CDs were thoroughly investigated. The resultant CDs exhibit green photoluminescence (PL) at 520 nm with absolute PL quantum yield (QY) of 21%. Moreover, the PL intensity proportionally depends on temperature in the range 150–360 K, which makes AA-derived CDs potentially useful for temperature sensing. • A mild bottom-up method is developed to synthesize 5 kinds of carbon dots (CDs). • CDs are prepared from carbonyl compounds under normal pressure and 50~95 °C. • CDs show blue/green fluorescence with maximum absolute quantum yield of 21%. • Acetylacetone-derived CDs show fluorescence response to temperature (150–360 K). • CDs might be applied as sensors for temperature detection. [ABSTRACT FROM AUTHOR]

Carbon dots have been rapidly developed as a kind of luminescent nanomaterials. However, methods for the synthesis of long-wavelength-emissive carbon dots are still not mature enough. Meanwhile, developing a fast and highly sensitive method to detect residual veterinary drugs in food is particularly significant for food safety. Herein, we report the facile fabrication of red-emissive carbon dots (R-CDs) for ratiometric sensing of veterinary drugs. With use of sorbitol and o -phenylenediamine as precursors, R-CDs was prepared via a one-pot solvothermal approach. The resulting R-CDs show mainly excitation-independent and dual-emissive photoluminescence (PL) located at 597 and 645 nm. Meanwhile, the PL quantum yield (QY) of R-CDs without further surface treatment is 33% under 540 nm excitation. Interestingly, the R-CDs exhibit fast fluorescence response to malachite green oxalate (MG oxalate), 1-aminohydantoin hydrochloride (AHD) and pefloxacin, which are abused widely and retained easily in animals. Ratiometric sensing of these veterinary drugs were successfully performed taking the advantage of dual-emissive PL property; the detection limits of MG oxalate, AHD and pefloxacin were 0.79, 0.25 and 0.85 μM, respectively. Highly red dual-emissive carbon dots are synthesized from one-pot solvothermal treatment and show ratiometric fluorescence sensing toward veterinary drugs. [Display omitted] • Red-emissive carbon dots (R-CDs) are synthesized via simple solvothermal treatment. • R-CDs show stable long-wavelength dual emission centered at 597 and 645 nm. • The as-prepared R-CDs have high photoluminescence quantum yield of 33%. • R-CDs exhibit fast sensitive selective fluorescence response to veterinary drugs. • R-CDs are potentially useful for ratiometric fluorescence sensors. [ABSTRACT FROM AUTHOR]